The great Florentine poet Dante Aligheri, in his masterwork The Divine Comedy, described a descent into the center of the earth that took him down into a vast dark chasm and through nine progressively smaller and colder concentric circles. At the planet's core he came face to face with Lucifer, frozen up to his chest in eternal ice.
Dante was neither the first nor the last to portray our planet's interior as a cold, hollow place, hostile to all living creatures. Through the earth sciences, we now know this to be fiction. The world below is neither cold nor hollow, and it teems with life to surprising depths.

Another fiction is the permanence of the continents and the oceans that divide them. Earth science has revealed these features to be the transient form of a surface that is continually, if incrementally, morphing itself. The poles of our planet wander, its magnetic field flickers, and the ground beneath our feet moves. All this happens because the world below is like a restless insomniac, never keeping still, never asleep.
Dante envisioned our planet's interior as an infernal reflection of his vision for Heaven. Today, earth scientists are discovering that far from being the reverse image of some other domain, the world below is unique unto itself.